Well the software that comes with most distros it far better than traditional windows software, open office is a much nicer office suite that ms office. Games can be run with a program called wine, as can a few windows programs if it is neccisery.
Ubuntu will suite you needs just fine for the hardware you have.
And linux is a very trustworthy OS it is used for many so called mission critical applications, it domminates the server market and is gaining strength in the home computing world I have been using linux full time for a while now but before that I have been playing around with it since 2000.